Circuit Description

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The knock sensor (KS) system enables the powertrain control module (PCM) to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The PCM monitors two KS. Each KS produces an AC voltage signal that varies at all engine speeds and loads. The PCM adjusts the spark timing based on the amplitude and the frequency of the KS signal. The PCM receives the KS signal through a signal circuit. The KS ground is supplied by the PCM through a low reference circuit. The PCM uses the KS signal to calculate the average voltage and then assigns a voltage range value. The PCM should monitor a normal KS signal within the assigned voltage range. If the PCM malfunctions in a manner that will not allow proper diagnosis of the KS system, this DTC will set.